While interparental relations are known to affect children's functioning directly (i.e., exposure to conflict), and indirectly through parenting, little is known about the specific processes responsible for these pathways. According to a new theory of emotional security, children's emotional security is conceptualized as a primary mediating process of the direct and indirect effects of interparental relations on child adjustment. The current proposal seeks to test the hypotheses derived from the core proposition of this theory. First, marital relations are proposed to play a direct etiological role in the development of child problems by threatening children's sense of emotional security in the interparental subsystem. Second, marital conflict, through its link with parenting disturbances, is proffered to indirectly lead to children's emotional insecurity and thus lay the foundation for their future psychological risk. Third, whereas constructive marital relations (e.g., conflict resolution, intimacy) are hypothesized to foster healthy family contexts and children's security and competency, destructive marital relations (e.g., hostility, child-rearing fights) are thought to have deleterious consequences for family and child functioning. Fourth, characteristics of the wider family context (e.g., parental depression, child temperament) are hypothesized to be salient in shaping parenting and marital disturbances and changing the nature of their impact on child adjustment. One hundred and sixty elementary school children and their parents will participate in a two-wave longitudinal study, with measurement occasions spaced 12 months apart. The tripartite operationalization of emotional security, specifically defined as emotion regulation, representations of family relations, and regulation of exposure to family affect, makes it particularly amenable to empirical testing across multiple family subsystems (e.g., marital, parent-child). All key constructs (i.e., marital relations, parenting, security, child adjustment) will be assessed using multiple methods, agents, and contexts. Adaptive and maladaptive dimensions of family relations and child functioning will be measured to identify a broad set of developmental mechanisms underlying competency, resilience, and risk in the early school years. The longitudinal design and repeated measures of constructs will allow for the delineation of prospective mediator and moderator models as well as the analysis of stability, change, and bidirectionality among family processes.